1. Field of the Invention
The present invention relates to tobacco conveyor belts for use in the manufacture of cigarettes and preferably, but not exclusively to so-called suction tapes.
2. Description of Related Art
During the manufacture of cigarettes a measured quantity of tobacco is taken up from a first tobacco conveyor belt by a second tobacco conveyor belt, i.e. the so-called suction tape, which generally has a width in the range from 0.5 to 1.5 cm. A diagrammatic illustration of a machine for making cigarettes is shown in FIG. 1. Each disposed line of tobacco is urged from the first tobacco conveyor belt 1 against the underside of a suction tape 2. The suction tape 2 runs within a groove in a suction box 3, the base of the groove being defined by a recessed ladder-like structure defined by two or more longitudinal rods linked together at spaced intervals by bars. The suction box 3 ensures that the suction tape 2 is urged upwardly against the recess ladder-like structure so that the tobacco is urged against the underside of the suction tape 2. The tobacco rod thus formed is removed from the suction tape 2 by means of inclined scraper blades 5, whereupon it falls onto enveloping cigarette paper supplied on a further conveyor belt, i.e. the so-called garniture belt 4.
Conventional suction tapes are woven endless, or alternatively are flat woven and then joined by ultrasonic means. Typically a single continuous weft (cross machine direction) yarn is provided thus presenting a large number of selvedges at the fabric edges. The selvedges are highly susceptible to abrasion accelerating fabric failure. The bunched nature of the warp (machine direction) yarns results in a somewhat non-uniform belt permeability and therefore a less even distribution of tobacco. Furthermore the narrowness of the belt requires complicated and expensive weaving machinery.